Non-invasive induction of bladder outlet obstruction in adult male rat model has bladder wall events similar to overactive bladder in human adult male

Mohamed Wishahi; Sarah Hassan; Dina Zaki; Nabawya Kamal; Mohamed Wishahi; Sarah Hassan; Dina Zaki; Nabawya Kamal

doi:10.3934/medsci.2025021

AIMS Medical Science

2025, Volume 12, Issue 4: 301-311. doi: 10.3934/medsci.2025021

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Research article

Non-invasive induction of bladder outlet obstruction in adult male rat model has bladder wall events similar to overactive bladder in human adult male

1.
Department of Urology, Theodor Bilharz Research Institute, P.O. 30, Cairo, Imbaba, Giza, 12411 Egypt
2.
Department of Pathology and Electron microscopy, Theodor Bilharz Research Institute, Cairo, Egypt
3.
Department of Anesthesia, Theodor Bilharz Research Institute, Cairo, Egypt

Received: 20 June 2025 Revised: 17 September 2025 Accepted: 11 October 2025 Published: 21 October 2025

Objectives
To determine the validity of the non-invasive, novel procedure of partial urethral obstruction in adult male rats to induce bladder outlet obstruction (BOO), this study investigated the reproducibility of non-surgical induction of partial urethral obstruction to induce BOO. Effects in the rat model were compared to those of an overactive bladder (OAB) in real-world adult human males. Previous reports of BOO induction in male rats applied an invasive technique through abdominal incision and dissection of the pelvic urethra, which deviates from real-world events of BOO in men.
Method
Sixteen adult male Sprague-Dawley rats (16 weeks old, 340 ± 10 g) were randomly divided into three groups: Bladder outlet obstruction group (n = 8), sham group (n = 4), and control group (n = 4). Eight rats underwent induction of BOO with the novel technique. At 8 weeks, the bladders of BOO, sham, and control groups were taken and examined histopathologically. The human study included tissue samples from three patients who had OAB secondary to neurogenic bladder dysfunction and had undergone surgical closure of vesicostomy with excision of the vesicostomy tract; tissue samples were examined histopathologically. Induction of BOO in adult male rats used a non-invasive technique that induces partial urethral occlusion via approaching the urethra at the root of the penis. The subsequent morphological and histological patterns of the male rat BOO were compared to patterns of human OAB.
Results
All rats survived, were active, and had no complications. Histological examination of tissue samples of the bladder wall with hematoxylin & eosin and Masson's trichrome stains showed thinner urothelium and condensation of collagen between muscle bundles. Human tissue samples showed similar cytoskeleton events.
Conclusions
The non-invasive technique to induce BOO in male rats proved to be safe, reproducible, and led to no complications. An increased collagen/smooth muscle ratio in the rat model was similar to that in humans. The results showed that the non-invasive procedure of BOO induction in male rats leads to identical cytoskeleton changes as in human OAB. The results indicate that this model could aid in understanding human male BOO and could be used for experimental studies of BOO in adult men.
- male rat model,
- bladder outlet obstruction,
- overactive bladder,
- experimental animal
Citation: Mohamed Wishahi, Sarah Hassan, Dina Zaki, Nabawya Kamal. Non-invasive induction of bladder outlet obstruction in adult male rat model has bladder wall events similar to overactive bladder in human adult male[J]. AIMS Medical Science, 2025, 12(4): 301-311. doi: 10.3934/medsci.2025021

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Abstract

Objectives

To determine the validity of the non-invasive, novel procedure of partial urethral obstruction in adult male rats to induce bladder outlet obstruction (BOO), this study investigated the reproducibility of non-surgical induction of partial urethral obstruction to induce BOO. Effects in the rat model were compared to those of an overactive bladder (OAB) in real-world adult human males. Previous reports of BOO induction in male rats applied an invasive technique through abdominal incision and dissection of the pelvic urethra, which deviates from real-world events of BOO in men.

Method

Sixteen adult male Sprague-Dawley rats (16 weeks old, 340 ± 10 g) were randomly divided into three groups: Bladder outlet obstruction group (n = 8), sham group (n = 4), and control group (n = 4). Eight rats underwent induction of BOO with the novel technique. At 8 weeks, the bladders of BOO, sham, and control groups were taken and examined histopathologically. The human study included tissue samples from three patients who had OAB secondary to neurogenic bladder dysfunction and had undergone surgical closure of vesicostomy with excision of the vesicostomy tract; tissue samples were examined histopathologically. Induction of BOO in adult male rats used a non-invasive technique that induces partial urethral occlusion via approaching the urethra at the root of the penis. The subsequent morphological and histological patterns of the male rat BOO were compared to patterns of human OAB.

Results

All rats survived, were active, and had no complications. Histological examination of tissue samples of the bladder wall with hematoxylin & eosin and Masson's trichrome stains showed thinner urothelium and condensation of collagen between muscle bundles. Human tissue samples showed similar cytoskeleton events.

Conclusions

The non-invasive technique to induce BOO in male rats proved to be safe, reproducible, and led to no complications. An increased collagen/smooth muscle ratio in the rat model was similar to that in humans. The results showed that the non-invasive procedure of BOO induction in male rats leads to identical cytoskeleton changes as in human OAB. The results indicate that this model could aid in understanding human male BOO and could be used for experimental studies of BOO in adult men.

Abbreviations

BOO

Bladder outlet obstruction

OAB

Overactive bladder

Haematoxylin and eosin

Ethical approval of the research and informed consent

The experimental study: The protocol and the study were done according to the requirement of National Research Council 2011 “Guide for the Care and Use of Laboratory Animals: Eighth Edition.” Washington, DC: The National Academies Press, and complied with the ARRIVE guidelines, AVMA Guidelines for the Euthanasia of Animals: 2020 Edition and approved by the Research Ethics Committee of Theodor Bilharz Research Institute (Cairo, Egypt) for the conduct of the animal experiments (TBRI- Protocol No: PT636).
The human study: The Research Ethics Committee of Theodor Bilharz Research Institute (Cairo, Egypt) approved the study (TBRI- Protocol No: PT 726). The study was conducted in compliance with the relevant laws and regulations, good clinical practice, and ethical principles as described in the World Medical Association's Declaration of Helsinki. The Patients consented to publish anonymously the data related to their samples.

Conflict of interest

The authors declare no conflict of interest.

References

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